Asked by Don'tknowtrig
Derive this identity from the sum and difference formulas for cosine:
sinasinb=1/2[cos(a-b)cos(a+b)]
Start with the right-hand side since it is more complex.
Calculations:
_____
_____
_____
Reason:
_____
_____
_____
sinasinb=1/2[cos(a-b)cos(a+b)]
Start with the right-hand side since it is more complex.
Calculations:
_____
_____
_____
Reason:
_____
_____
_____
Answers
Answered by
Reiny
look at the end of your last post of this same thing
https://www.jiskha.com/display.cgi?id=1527528235
https://www.jiskha.com/display.cgi?id=1527528235